The present invention relates to native, site specifically mutated, and synthetic peptides comprising portions of the human androgen receptor and composition thereof. The invention also relates to antibodies raised against these peptides and polynucleotides encoding these peptides. Also provided are methods for synthesizing derivatives of these peptides and their use as anti-androgen compositions in the treatment and/or prevention of prostate and/or breast cancers, preparation of pharmaceutical compositions, diagnostic kits, and development of related assays for use in anticancer therapies.